Instead of Weight Training (430 calories)...
Try Playing in the Park (430 calories)
With the exploding popularity of boot camps and DIY interval workouts, every park is now an ersatz gym. And some are pretty advanced: The new Fitness Zones from the Trust for Public Land even offer free outdoor elliptical machines and other Nautilus-type equipment (there are currently 81 locations, mostly in California and Florida, with more coming soon to Newark, Boston and other cities). You can still get a serious muscle-building workout with just a park bench: Try a series of push-ups, triceps dips and step-ups. Jungle gyms are also great way to practice pull-ups. Start with your feet on the ground until you get the mechanics of the move, then do a little hop for momentum, and eventually (3 months, maybe), you'll be proving to yourself (and to researchers) that women can do them.
Next: 4 playful workouts the kid inside of you will love